Portable flow meter for low volume applications

ABSTRACT

An apparatus is disclosed that may include a substrate that may have a surface, a channel of a volume that may be defined, at least in part, by the substrate, wherein the channel may have a first end and a second end, a valve may be coupled to the channel at the first end, wherein the valve may be configured to allow a fluid to pass into the channel when the valve is open, and a continuity detector, which may be coupled to the channel at the second end, wherein the continuity detector may be activated when the fluid contacts the continuity detector, wherein the continuity detector may further be configured to provide a signal to close the valve and remove the fluid from the channel. A method for calculating a rate of flow of a fluid collected from a bodily surface into a body-worn device is disclosed.

BACKGROUND

Flow meters calculate flow rates, which is the volume of fluid thatpasses through a measurement point during a period of time. For example,utility companies may use flow meters to determine how much water ahousehold used during a month to calculate monthly usage fees.

Measuring the flow rate of low volumes of fluids with low flow rates maybe more difficult than measuring the flow rate of large volumes. Surfacetension of the fluid and/or surfaces of the flow meter may affect theobserved flow rate of the flow meter. For example, a plant may producesecretions on its stem. The stem may have a small observable area, andthe secretions may occur over hours or days. Determining a secretionrate of the plant with traditional flow meters may not be feasible.

SUMMARY

Techniques are generally described that include apparatuses, methods,and systems. An example apparatus may include a substrate which may havea surface, a channel which may have a volume defined, at least in part,by the substrate, wherein the channel may have a first end and a secondend, a valve coupled to the channel at the first end, wherein the valvemay be configured to allow a fluid to pass into the channel when thevalve is open, and a continuity detector coupled to the channel at thesecond end, wherein the continuity detector may be activated when thefluid contacts the continuity detector, wherein the continuity detectormay be further configured to provide a signal to close the valve andremove the fluid from the channel.

An example method may include collecting a fluid from a bodily surfaceinto a body-worn device, filling a channel of the body-worn device withthe fluid, measuring, using the body-worn device, a time it takes tofill the channel with the fluid, removing the fluid from the channel,and calculating, using the body-worn device, a rate of flow of the fluidbased, at least in part, on the time it takes to fill the channel withthe fluid.

An example system may include a sensor that may be configured to monitora flow of a fluid from a bodily surface area through a channel of avolume, a first processor that may be configured to receive signals fromthe sensor and calculate a flow rate of the fluid, and a computingdevice, including a second processor that may be configured to receivethe flow rate of the fluid from the first processor and combine the flowrate of the fluid with additional data to calculate a health status of auser.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several examples in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings, in which:

FIG. 1 is a schematic illustration of an example flow meter;

FIG. 2 is a schematic illustration of an example sensor;

FIG. 3 is a schematic illustration of an example absorbent material;

FIG. 4 is a schematic illustration of an example sensor in examplestages of operation;

FIG. 5 is a flow chart of an example method;

FIG. 6 is a block diagram illustrating an example computing device thatis arranged for monitoring a flow rate; and

FIG. 7 is a block diagram illustrating an example computer programproduct that is arranged to store instructions for monitoring a flowrate;

all arranged in accordance with at least some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative examples described in the detaileddescription, drawings, and claims are not meant to be limiting. Otherexamples may be utilized, and other changes may be made, withoutdeparting from the spirit or scope of the subject matter presentedherein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in theFigures, can be arranged, substituted, combined, separated, and designedin a wide variety of different configurations, all of which areimplicitly contemplated herein.

This disclosure is drawn, inter alia, to methods, systems, products,devices, and/or apparatus generally related to an apparatus that mayinclude a substrate that may have a surface, a channel of a volume thatmay be defined, at least in part, by the substrate, wherein the channelmay have a first end and a second end, a valve may be coupled to thechannel at the first end, wherein the valve may be configured to allow afluid to pass into the channel when the valve is open, and a continuitydetector, which may be coupled to the channel at the second end, whereinthe continuity detector may be activated when the fluid contacts thecontinuity detector, wherein the continuity detector may further beconfigured to provide a signal to close the valve and remove the fluidfrom the channel.

FIG. 1 is a schematic illustration an example flow meter 100 arranged inaccordance with at least some embodiments described herein. The flowmeter 100 includes a sensor 160 that may be enclosed in a substrate 150.The substrate 150 may include an upper layer 105 disposed over thesensor 160. FIG. 1 shows the upper layer 105 removed from the substrate150 for clarity. The sensor 160 may include a channel 110 withelectrodes 115 coupled to the channel 110, an opening 120 in thechannel, an I/O port 130, and a continuity detector 155 spanning thechannel 110. The substrate 150 may enclose an absorbent material 145,which may be seen through cutaway 140 in FIG. 1. The opening 120 maycouple the channel 110 to the absorbent material 145. A seal 135 may becoupled to a lower surface of the substrate 150. The various componentsdescribed in FIG. 1 are merely examples, and other variations, includingeliminating components, combining components, and substitutingcomponents are all contemplated.

In some embodiments, the upper layer 105 of the substrate 150 is aremovable lid placed over the sensor 160. In some embodiments, the upperlayer 105 is permanently coupled to the substrate 150. In someembodiments, the upper layer 105 is the same material as the substrate150. In some embodiments, the upper layer 105 and the substrate 150 areimplemented using different materials. The upper layer 105 and substrate150 may be implemented using a polymer, glass, silicone, and/or metal.Other materials may also be used.

In some embodiments, the sensor 160 may include a piezoelectric materialthat at least partially defines the channel 110. In some examples, thesubstrate 150 at least partially defines the channel 110 and thesubstrate 150 is implemented using a piezoelectric material. In someexamples, the piezoelectric material may be included in the substrate150. The piezoelectric material may be activated by the electrodes 115.The application of an electrical charge through the electrodes 115 maycause the piezoelectric material to contract and cause the channel 110and opening 120 to open and close. In some embodiments, thepiezoelectric material may be replaced by an electromagnetic actuatorthat may be used to open and close the channel 110 and opening 120.

In some embodiments, the electrodes 115 may be activated by a signalreceived from the continuity detector 155. The electrodes 115 maydeactivate when the signal is no longer received from the continuitydetector 155. In some embodiments, the electrodes may be activated by acontrol signal received from the I/O port 130. In some embodiments, thecontinuity detector 155 may send signals to the I/O port 130. In someembodiments, the I/O port 130 may couple the flow meter 100 to aprocessor and/or other computing device.

In some embodiments, the seal 135 may extend around a perimeter of thelower surface of the substrate 150. The seal 135 may be implementedusing rubber, silicone, and/or another non-porous elastomer. In someembodiments, the seal 135 may allow the flow meter 100 to adhere to asurface. In some embodiments, the flow meter 100 is held in placeagainst a surface by a strap (not shown). In some embodiments, the seal135 may be substantially impermeable and may prevent fluids fromentering or exiting the flow meter 100 from the lower surface of thesubstrate 150. In some embodiments, the seal 135 may define an area of asurface over which a flow rate is measured. In some embodiments, thearea may be between 0.1 and 5 square centimeters. Other areas may alsobe possible.

In some embodiments, the substrate 150 has an interior portion that mayat least partially enclose the absorbent material 145. The absorbentmaterial 145 may extend from the lower surface of the substrate 150 tothe opening 120 of the channel 110. In some embodiments, the absorbentmaterial 145 may conduct fluids proximate to the lower surface of thesubstrate 150 to the opening 120.

In operation, the flow meter 100 may be coupled to a surface over whicha fluid flow rate is to be measured. Examples include, but are notlimited to, human skin, a leaf, and/or a membrane. The lower surface ofthe flow meter 100 may be placed in contact with the surface. The seal135 may adhere to the surface and/or a strap (not shown) may be appliedto the flow meter 100 to maintain contact with the surface. The seal 135may enclose an area of the surface over which the flow meter 100 isplaced. The seal 135 may prevent fluid emitted from the surface areaunder the flow meter 100 from flowing out under the lower surface of theflow meter 100. The seal 135 may further prevent fluid emitted from thesurface outside the area under the flow meter 100 from entering the flowmeter 100 through the lower surface. This may allow fluid flow to bemeasured from a fixed area of the surface.

Fluid emitted by the surface area under the flow meter 100 may contactthe absorbent material 145. The absorbent material 145 may conduct thefluid from the surface to the opening 120. The fluid may flow throughthe opening 120 into the channel 110 of the sensor 160. As more fluid isemitted from the surface area under the flow meter 100, more fluid maybe conducted by the absorbent material 145 to the channel 110. The fluidmay fill the channel 110 to where the fluid contacts the continuitydetector 155. The continuity detector 155 may send a signal to theelectrodes 115 and/or the I/O port 130 when the fluid contacts thecontinuity detector 155. In response to a signal from the continuitydetector 115 and/or I/O port 130, the electrodes 115 may apply a chargeto a piezoelectric material of the channel 110. The charge may cause thepiezoelectric material to activate.

The piezoelectric material may close the opening 120, which may preventfluid in the channel 110 from flowing back into the absorbent material145. The piezoelectric material may also close the body of the channel110 such that fluid is forced out of the end of the channel 110proximate to the continuity detector 155. In some embodiments, activelyremoving the fluid from the channel 110 may prevent surface tensionand/or other interactions between the fluid and the channel 110 frominterfering with measuring a flow rate of the fluid emitted from thesurface.

In some embodiments, the expelled fluid may drip down the outer surfaceof the substrate 150 of the flow meter 100. The expelled fluid may beprevented from reentering the flow meter 100 by seal 135. Optionally, insome embodiments, the expelled fluid may be collected in a receptacle(not shown) coupled to the flow meter 100. The receptacle may retain thefluid for future analysis. Once the fluid has been expelled from theflow meter 100, the electrodes 115 may stop applying a charge to thepiezoelectric material, which may then return to a rest state. In therest state, the channel 110 and opening 120 are opened, and fluidemitted from the surface may continue to enter the channel 110. Thefluid may again be expelled when it contacts the continuity detector155.

In some embodiments, the flow rate of the fluid emitted from the surfacemay be calculated based, at least in part, on the number of times thefluid is expelled from the channel during a period of time. In someembodiments, a clock (not shown) may be used to measure the time ittakes to fill the channel 110. In some embodiments, the clock may becoupled to the flow meter 100 through I/O port 130. In some embodiments,the clock is included in a computing device coupled to the I/O port 130.The clock may receive a signal from the continuity detector 155 via theI/O port 130, which may signal that the channel 110 has been filled withthe fluid. In some embodiments, the clock may be configured to measure atime period and reset each time the continuity detector is activated. Insome embodiments, the clock may be coupled to a processor. In someembodiments, the clock may be integrated with the processor. In someembodiments, the processor is included in the computing device. Theprocessor may be configured to receive the time period from the clockand calculate a rate of flow of the fluid through the channel 110, basedat least in part on the time period from the clock. In some embodiments,the flow rate may further be based at least in part on the volume of thechannel 110.

FIG. 2 is a schematic illustration of an example sensor 200 arranged inaccordance with at least some embodiments described herein. In someembodiments, sensor 200 may be used to implement the sensor 160illustrated in FIG. 1. In some embodiments, the sensor 200 may beincluded on a substrate 250. In some embodiments, the substrate 250 maybe implemented with the substrate 150 illustrated in FIG. 1. FIG. 2shows a piezoelectric material 210 that at least partially defines achannel 275. A continuity detector 255 may be coupled to thepiezoelectric material 210. Electrodes 215 may also be coupled to thepiezoelectric material 210. A valve 220 may be located at one end of thechannel 275 opposite the continuity detector 255. A stop valve 270 maybe included in the channel 275 near the continuity detector 255 at anend opposite the valve 220. The electrodes 215 and/or continuitydetector 255 may be coupled to an I/O port 235. In some embodiments, thesensor 200 may be coupled to a computing device via the I/O port 235.The various components described in FIG. 2 are merely examples, andother variations, including eliminating components, combiningcomponents, and substituting components are all contemplated.

In some embodiments, the sensor 200 may be configured such that a fluidmay enter the channel 275 via the valve 220 and flow through the channel275 toward the continuity detector 255. In some embodiments, fluid maybe prevented from entering the channel 275 via the stop valve 270. Insome embodiments, fluid may be prevented from exiting the channel 275via the stop valve 270. In some embodiments, fluid may exit the channel275 via the stop valve 270 when the piezoelectric material 210 isactivated. In some embodiments, the channel 275 may contract and expelthe fluid from the channel 275 when the piezoelectric material 210 isactivated. In some embodiments, the piezoelectric material 210 isactivated by the electrodes 215. The electrodes 215 may activate thepiezoelectric material 210 when it receives a signal from the continuitydetector 255. The continuity detector 255 may send a signal to activatethe piezoelectric material 210 when fluid in the channel 275 contactsthe continuity detector 255.

In some embodiments, the channel 275 may have a volume defined at leastin part by the piezoelectric material 210. In some embodiments, thechannel 275 may have a volume defined at least in part by the substrate250. In some embodiments, both the piezoelectric material 210 and thesubstrate 250 may at least partially define the volume. In someembodiments, the volume of the channel 275 may be about 10 nanoliters toabout 100 nanoliters. In some embodiments, the volume of the channel 275may be about 100 nanoliters to about 1,000 nanoliters. In someembodiments, the volume of the channel 275 may be about 1 microliter toabout 10 microliters. Other volumes may also be possible.

In some embodiments, the fluid may only pass in one direction throughthe channel 275. In some embodiments, the valve 220 is a one-way valvethat only allows fluids to enter the channel 275. In some embodiments,the valve 220 is an opening in the channel 275. In some embodiments, thestop valve 270 is a hydrophobic material. In some examples, the stopvalve 270 is made of siloxane. In some embodiments, the stop valve 270is omitted, and the end of the channel 275 proximate the continuitydetector 255 is open. In some embodiments, the valve 220 is configuredto close before the stop valve 270 is opened when the piezoelectricmaterial 210 is activated.

In some embodiments, additional sensors (not shown) may be included inthe channel 275 for additional data acquisition. In some embodiments,the continuity detector 255 may collect additional data. Additional datamay include detecting and/or quantifying analytes of interest in thefluid, temperature of the fluid, pH level of the fluid, and/or otherfluid properties. Examples of analytes of interest may include, but arenot limited to, lactate, potassium, sodium, glucose, proteins, and/orother chemicals. In some embodiments, the sensors are electrochemicalsensors. In some embodiments, the sensors are optical sensors. In someembodiments, multiple sensor types may be included in the channel 275.

In some embodiments, the electrodes 215, continuity detector 255, and/oradditional sensors may be coupled to the I/O port 235. The I/O port 235may receive and/or send signals to the electrodes 215, continuitydetector 255, and/or additional sensors. In some embodiments, the I/Oport 235 may receive data signals from the continuity detector 255and/or additional sensors. The I/O port 235 may provide the data signalsto a computing device configured to store and/or process the data fromthe data signals. The I/O port 235 may provide the data signals via awired connection, a wireless connection, or both. The computing devicemay be configured to analyze the data to calculate a flow rate of thefluid. The computing device may be configured to analyze the data and/oradditional data to determine a health status of a user. The computingdevice may send control signals to the sensor 200 via the I/O port 235in some embodiments. For example, the computing device may send acontrol signal to the electrodes 215 to apply a charge to thepiezoelectric material 210. In some embodiments, additional controlsignals may be sent by the computing device.

FIG. 3 is a schematic illustration of an example absorbent material 300.The absorbent material 300 may be used as the absorbent material 145 inFIG. 1. FIG. 3 shows a conduit system 345 coupled to an opening 320. Thevarious components described in FIG. 3 are merely examples, and othervariations, including eliminating components, combining components, andsubstituting components are all contemplated.

In some embodiments, the absorbent material 300 may be implementedutilizing a sponge or a hydrogel. In some embodiments, the absorbentmaterial 300 is cotton. In some embodiments, other absorbent materialsor combination of absorbent materials are utilized. In some embodiments,as illustrated in FIG. 3, the absorbent material 300 may be a printedand/or etched branched conduit system 345 of converging capillaries. Theconduit system 345 may draw fluid from a surface and direct the fluidtoward the opening 320. The fluid may be drawn by capillary actionand/or some other force. In some embodiments, the conduit system 345 isetched and/or printed in a semi-rigid polymer or hardened elastomer.

In some embodiments, the absorbent material 300 is saturated with afluid prior to operation of a flow meter (not shown in FIG. 3).Pre-saturating the absorbent material 300 may reduce or eliminate lagand/or priming time of the flow meter. In some embodiments, at thesaturation point of the absorbent material 300, any fluid added toabsorbent material 300 may displace an equivalent amount of fluid at theopening 320. In some embodiments, the priming fluid used to pre-saturatethe absorbent material 300 is distilled water. In some embodiments, thepriming fluid is saline.

In some embodiments, the opening 320 is at the top of the absorbentmaterial 300. In some embodiments, the opening 320 is on a side of theabsorbent material 300. In some embodiments, the opening 320 may be anopening in a substrate, such as the substrate 150 in FIG. 1. In someembodiments, the absorbent material 300 is cone-shaped. In someembodiments, the absorbent material 300 is cylinder shaped. Other shapesmay be possible. In some embodiments, the absorbent material 300 may beat least partially enclosed in a substrate. In some embodiments, theabsorbent material 300 may be removably coupled to the substrate, suchthat the absorbent material 300 may be disposable and be replaced by anew absorbent material after one or more uses. In some embodiments, theabsorbent material 300 may be adjacent to a surface from which fluidflow is to be measured. The absorbent material 300 may conduct a fluidfrom the surface to the opening 320. The fluid may then pass through theopening 320. In some embodiments, the opening 320 may lead to and may bein fluid communication with a channel in a flow meter such as thechannel 275 in FIG. 2.

FIG. 4 is a schematic illustration of an example sensor 400 in examplestages of operation. The sensor 400 may be similar to the sensor 200 inFIG. 2. In some embodiments, the sensor 160 in FIG. 1 may be implementedusing sensor 400. FIG. 4 shows a piezoelectric material 410 that atleast partially defines a channel 475. A continuity detector 455 may becoupled to the piezoelectric material 410. Electrodes 415 may also becoupled to the piezoelectric material 410. A valve 420 may be defined atone end of the channel 475 opposite the continuity detector 455. A stopvalve 470 may be included in the channel 475 near the continuitydetector 455 at an end opposite the valve 420. A fluid 405 may enter thechannel 475 via valve 420. The various components described in FIG. 4are merely examples, and other variations, including eliminatingcomponents, combining components, and substituting components are allcontemplated.

In some embodiments, the sensor 400 may begin in an empty-rest state480. In state 480, little or no fluid 405 is present in the channel 475.In this state 480, the electrodes 415 are not active, and the electrodes415 do not provide a charge to the piezoelectric material 410. Thepiezoelectric material 410 may be in a rest state when no charge isapplied by the electrodes 415. When the piezoelectric material 410 is ina rest state, the valve 420 may allow fluid 405 to enter the channel475, and the channel 475 may define a fixed volume. In some embodiments,the continuity detector 455 may detect a high resistance across thechannel 475 in state 480. In some embodiments, the continuity detector455 may be an open circuit in state 480.

In some embodiments, as fluid 405 begins to enter the channel 475, thesensor 400 may transition to state 485. The components may have similarpositions and properties as in state 480. Once fluid 405 fills thechannel 475 to the location where the continuity detector 455 islocated, the sensor 400 enters state 490. In some embodiments, thecontinuity detector 455 may detect a low resistance across the channel475 in state 490. In some embodiments, the fluid 405 may conduct acurrent across the channel 475 at the continuity detector 455. In someembodiments, the fluid 405 may close a circuit of the continuitydetector 455. In response, in some embodiments, the continuity detector455 may send a signal to a processor (not shown) via I/O port 435 and/orthe electrodes 415. In some embodiments, the electrodes 415 receive asignal from the processor via I/O port 435. The processor may be coupledto the sensor 400 via I/O port 435. In some embodiments, the processormay be included in a computing device.

In some embodiments, once the electrodes 415 receive a signal, thesensor 400 may transition to state 495. In some embodiments, the signalreceived by the electrodes 415 may be an activation signal. In responsethe activation signal, the electrodes 415 may apply an electrical chargeto the piezoelectric material 410. The piezoelectric material 410 may beactivated in response to the electrical charge from the electrodes. Insome embodiments, the piezoelectric material 410 may close the valve 420and close the channel 475, expelling the fluid 405 from the channel 475via the stop valve 470. Once the fluid 405 has been removed, the sensor400 may return to state 480. In some embodiments, the sensor 400 maycycle through the states until fluid 405 no longer fills the channel475. In some embodiments, the sensor 400 may act as a one-way pump of aknown volume of the fluid 405.

In some embodiments, the continuity detector 455 may be coupled to aclock (not shown). The clock may be coupled to or included in aprocessor (not shown). The clock may count until it receives a signalfrom the continuity detector 455. In some embodiments, the clock mayreceive a signal from the continuity detector at state 490. When theclock receives the signal from the continuity detector 455, it may passthe count and/or other measure of time to a processor and/or a memory.In some embodiments, the clock may also reset when it receives thesignal from the continuity detector 455 and begin counting again whenthe sensor 400 returns to state 480.

In some embodiments, a flow rate may be calculated based, at least inpart, on the time the fluid 405 took to fill the channel 475. If thevolume of the channel 475 is fixed and the time the fluid 405 took tofill the channel 475 is measured, the flow rate may be calculated interms of volume/time in some embodiments. If an area over which thefluid 405 was collected is fixed, the flow rate may be calculated interms of volume/time/area. In some embodiments, the clock, processor,and/or memory may be coupled to the flow meter via an I/O port such asI/O port 130 in FIG. 1. In some embodiments, the clock, processor,and/or memory may be included in the flow meter. In some embodiments,the flow meter may communicate wirelessly with the clock, processor,and/or memory, which may be located on one or more separate devices.Separate devices may include, but are not limited to a personalcomputer, a watch, a smart phone, and/or laptop.

In some embodiments, the flow meter shown in FIG. 1 may include thesensor 400 shown in FIG. 4. The flow meter may be coupled to a surfaceto measure the flow rate of a fluid from the surface. In someembodiments, a flow meter according to at least one embodiment may becoupled to a bodily surface. The flow meter may be used to calculate arate of fluid flow on the bodily surface. For example, the rate ofperspiration (e.g. sweat) on a subject's skin may be monitored with theflow meter. Monitoring the perspiration of a subject may provideinformation about the subject's exertion and/or hydration status. Theprevious example is for explanatory purposes only. It should not beinterpreted as limiting the scope of the disclosure.

In some embodiments, the flow meter may further include or be coupled toadditional sensors. For example, a heart rate monitor, exerciseintensity, thermometer, oxygen sensor, and/or glucose monitor may becoupled to the flow meter. Data from the additional sensors may also becoupled to a processor and/or other computing device. The processorand/or computing device may use data from one or more of the sensors tocalculate a health status of a user.

FIG. 5 is a flow chart of an example method 500. An example method mayinclude one or more operations, functions or actions as illustrated byone or more of blocks 505, 510, 515, 520, and/or 525. The one or more ofthe operations described in the blocks 505 through 525 may be performedin response to execution (such as by one or more processors describedherein) of computer-executable instructions stored in acomputer-readable medium, such as a computer-readable medium of acomputing device or some other controller similarly configured.

An example process may begin with block 505, which recites “Collect afluid from a bodily surface into a body-worn device.” Block 505 may befollowed by block 510, which recites “Fill a channel with the fluid.”Block 510 may be followed by block 515, which recites, “Measure a timeit takes to fill the channel with the fluid.” Block 515 may be followedby block 520, which recites, “Remove the fluid from the channel.” Block520 may be followed by block 525, which recites, “Calculate a rate offlow of the fluid.”

The blocks included in the described example methods are forillustration purposes. In some embodiments, the blocks may be performedin a different order. In some other embodiments, various blocks may beeliminated. In still other embodiments, various blocks may be dividedinto additional blocks, supplemented with other blocks, or combinedtogether into fewer blocks. Other variations of these specific blocksare contemplated, including changes in the order of the blocks, changesin the content of the blocks being split or combined into other blocks,etc. In some examples, block 525 “Calculate a rate of flow of the fluid”may be performed before block 520 “Remove the fluid from the channel.”

Block 505 recites, “Collect a fluid from a bodily surface into abody-worn device.” A body-worn device may be a flow meter. In someembodiments, the body-worn device may be the flow meter 100 asillustrated in FIG. 1. A bodily surface may be human skin in someembodiments. In some embodiments, the fluid may be perspiration. Theflow meter may be coupled to the bodily surface by a seal, such as seal135 in FIG. 1. In some embodiments, the flow meter may be coupled to thebodily surface by a strap. In some embodiments, an absorbent materialincluded in the flow meter collects the fluid from the bodily surfaceand conducts it to a sensor in the flow meter, such as sensor 400 inFIG. 4.

Block 510 recites, “Fill a channel with the fluid.” The channel may beincluded in the body-worn device. In some embodiments, the fluidcollected by the absorbent material enters the channel through a valveand/or opening at one end of the channel. In some embodiments, the fluidmay only flow in one direction through the channel.

Block 515 recites, “Measure a time it takes to fill the channel with thefluid.” In some embodiments, a timer and/or clock measures the time fromwhen the collection of the fluid begins until the channel is full. Insome embodiments, a continuity detector, such as continuity detector 455in FIG. 4, detects when the channel is full. The continuity detector maysend a signal to the clock and/or timer that indicates the channel hasbeen filled by the fluid. The clock and/or timer may transmit the timemeasured to fill the channel to a processor, a database, a memory,and/or another destination. In some embodiments, the clock and/or timermay begin measuring time until another signal is received from thecontinuity detector.

Block 520 recites, “Remove the fluid from the channel.” Once the channelhas been filed by the fluid, the channel is emptied. In someembodiments, the channel is emptied by applying an electric charge to apiezoelectric material that at least partially defines the channel. Thepiezoelectric material may close the channel and cause the fluid to beexpelled from the channel when the electric charge is applied. In someembodiments, the piezoelectric material may be omitted, and anelectromagnetic actuator may be used to close the channel and expel thefluid.

Block 525 recites, “Calculate a rate of flow of the fluid.” A processormay receive the time measurement from the clock and/or timer in someembodiments. In some embodiments, the processor may calculate a relativefluid flow rate (e.g. channel fills/minute). In some embodiments, thevolume of the channel may be known, and the processor may calculate anabsolute fluid flow rate (e.g. nanoliters/minute). In some embodiments,the processor may calculate a relative fluid flow rate per a unit area(e.g. channel fills/minute/device area). In some embodiments, the areaof a bodily surface may be known. In some embodiments, channel volumeand area over which fluid was collected may be known, and the processormay calculate an absolute fluid flow rate per area (e.g.nanoliters/minute/centimeters squared). In some embodiments, the fluidmay include sweat, and a rate of perspiration of a user may becalculated based, at least in part, on the rate of flow of the fluid.

FIG. 6 is a block diagram illustrating an example computing device 600that is arranged for operating a flow meter and/or calculating a flowrate in accordance with the present disclosure. In some embodiments, thecomputing device 600 may be arranged to receive signals from a sensorconfigured to monitor a flow of a fluid from a bodily surface areathrough a channel of a volume and calculate a flow rate of the fluidand/or receive the flow rate of the fluid and combine the flow rate ofthe fluid with additional data to calculate a health status of a user.For example, the sensor from which the computing device 600 receivessignals may be configured as any of the sensor examples disclosed hereinsuch as the sensor 200 or 400. In a very basic configuration 601,computing device 600 typically includes one or more processors 610 andsystem memory 620. A memory bus 630 may be used for communicatingbetween the processor 610 and the system memory 620.

Depending on the desired configuration, processor 610 may be of any typeincluding but not limited to a microprocessor (μP), a microcontroller(μC), a digital signal processor (DSP), or any combination thereof.Processor 610 may include one more levels of caching, such as a levelone cache 611 and a level two cache 612, a processor core 613, andregisters 614. An example processor core 613 may include an arithmeticlogic unit (ALU), a floating point unit (FPU), a digital signalprocessing core (DSP Core), or any combination thereof. An examplememory controller 615 may also be used with the processor 610, or insome implementations the memory controller 615 may be an internal partof the processor 610.

Depending on the desired configuration, the system memory 620 may be ofany type including but not limited to volatile memory (such as RAM),non-volatile memory (such as ROM, flash memory, etc.) or any combinationthereof. System memory 620 may include an operating system 621, one ormore applications 622, and program data 624. Application 622 may includea fluid flow rate calculation procedure 623 that is arranged tocalculate a fluid flow rate of a collected fluid as described herein.Program data 624 may include channel volume, fluid collection area,and/or other information useful for the implementation of the fluid flowrate calculation procedure. In some embodiments, application 622 may bearranged to operate with program data 624 on an operating system 621such that any of the procedures described herein may be performed. Thisdescribed basic configuration is illustrated in FIG. 6 by thosecomponents within dashed line of the basic configuration 601.

Computing device 600 may have additional features or functionality, andadditional interfaces to facilitate communications between the basicconfiguration 601 and any required devices and interfaces. For example,a bus/interface controller 640 may be used to facilitate communicationsbetween the basic configuration 601 and one or more storage devices 750via a storage interface bus 641. The storage devices 650 may beremovable storage devices 751, non-removable storage devices 652, or acombination thereof. Examples of removable storage and non-removablestorage devices include magnetic disk devices such as flexible diskdrives and hard-disk drives (HDD), optical disk drives such as compactdisk (CD) drives or digital versatile disk (DVD) drives, solid statedrives (SSD), and tape drives to name a few. Example computer storagemedia may include volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage ofinformation, such as computer readable instructions, data structures,program modules, or other data.

System memory 620, removable storage 651 and non-removable storage 652are all examples of computer storage media. Computer storage mediaincludes, but is not limited to, RAM, ROM, EEPROM, flash memory or othermemory technology, CD-ROM, digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which maybe used to store the desired information and which may be accessed bycomputing device 600. Any such computer storage media may be part ofcomputing device 600.

Computing device 600 may also include an interface bus 642 forfacilitating communication from various interface devices (e.g., outputinterfaces, peripheral interfaces, and communication interfaces) to thebasic configuration 601 via the bus/interface controller 640. Exampleoutput devices 660 include a graphics processing unit 661 and an audioprocessing unit 662, which may be configured to communicate to variousexternal devices such as a display or speakers via one or more A/V ports663. Example peripheral interfaces 670 include a serial interfacecontroller 671 or a parallel interface controller 672, which may beconfigured to communicate with external devices such as input devices(e.g., keyboard, mouse, pen, voice input device, touch input device,etc.) or other peripheral devices (e.g., printer, scanner, etc.) via oneor more I/O ports 673. An example communication device 680 includes anetwork controller 681, which may be arranged to facilitatecommunications with one or more other computing devices 690 over anetwork communication link via one or more communication ports 682.

The network communication link may be one example of a communicationmedia. Communication media may typically be embodied by computerreadable instructions, data structures, program modules, or other datain a modulated data signal, such as a carrier wave or other transportmechanism, and may include any information delivery media. A “modulateddata signal” may be a signal that has one or more of its characteristicsset or changed in such a manner as to encode information in the signal.By way of example, and not limitation, communication media may includewired media such as a wired network or direct-wired connection, andwireless media such as acoustic, radio frequency (RF), microwave,infrared (IR) and other wireless media. The term computer readable mediaas used herein may include both storage media and communication media.

Computing device 600 may be implemented as a portion of a small-formfactor portable (or mobile) electronic device such as a cell phone, apersonal data assistant (PDA), a personal media player device, awireless web-watch device, a personal headset device, an applicationspecific device, or a hybrid device that include any of the abovefunctions. Computing device 600 may also be implemented as a personalcomputer including both laptop computer and non-laptop computerconfigurations.

FIG. 7 is a block diagram illustrating an example computer programproduct 700 that is arranged to store instructions for operating a flowmeter and/or calculating a fluid flow rate in accordance with thepresent disclosure. The signal bearing medium 702 which may beimplemented as or include a computer-readable medium 706, a computerrecordable medium 708, a computer communications medium 710, orcombinations thereof, stores programming instructions 704 that mayconfigure the processing unit to perform all or some of the processespreviously described. These instructions may include, for example, oneor more executable instructions for measuring a time it takes to fill achannel with a fluid, removing the fluid from the channel, and/orcalculating a rate of flow of the fluid, based at least in part, on thetime it takes to fill the channel with fluid.

In some embodiments, the computer program product 700 may further storeinstructions for utilizing data from additional sensors to providecomprehensive real time and cumulative indications of a health status,such as hydration status. Additional data may include hydration status,exercise intensity, movement, heart rate, temperature, and/or sweatcomposition. Data from other sources may also be utilized by thecomputer program product in some embodiments, including geolocation,weather, diet, age, gender, and/or weight of a user. In someembodiments, the computer program product 700 may store instructions forproviding information on a health status for a given amount of time. Insome embodiments, the amount of time is an hour, a day, or a minute. Insome embodiments, the computer program product 700 may store instructionfor continuously providing information on a health status of a user. Insome embodiments, the computer program product 700 may be configured toprovide text and/or graphical information to a user on a display coupledto a computing device. In some embodiments, the information may bebased, at least in part, on the calculated fluid flow rate and/oradditional data.

In some embodiments, a system may include a sensor configured to monitora flow of a fluid from a bodily surface area through a channel of avolume, a first processor configured to receive signals from the sensorand calculate a flow rate of the fluid, a computing device, including asecond processor configured to receive the flow rate of the fluid fromthe first processor and combine the flow rate of the fluid withadditional data to calculate a health status of a user. In someembodiments, the computing device may be implemented using the computingdevice 600 illustrated in FIG. 6. In some embodiments, the computingdevice is integrated with the sensor. In some embodiments, the firstand/or second processor may be configured to execute at least a portionof a computer product. In some embodiments, the computer product may beimplemented as computer product 700 illustrated in FIG. 7. In someembodiments, the additional data may include at least one of atemperature, an exercise intensity of the user, or a heart rate of theuser. In some embodiments, the second processor may be furtherconfigured to calculate a perspiration rate of the user based, at leastin part, on the flow rate of the fluid. In some embodiments, the healthstatus may be a hydration status of the user. In some embodiments, thecomputing device may be configured to receive the additional data fromadditional sensors that may be different from the sensor configured tomonitor the flow of the fluid. In some embodiments, the first processormay be wirelessly coupled to the computing device.

In some embodiments, the sensor may be included in an apparatus. In someembodiments, the apparatus may be implemented using flow meter 100illustrated in FIG. 1. In some embodiments, the apparatus may include asubstrate which may have a surface, a channel which may have a volumedefined, at least in part, by the substrate, wherein the channel mayhave a first end and a second end, a valve coupled to the channel at thefirst end, wherein the valve may be configured to allow a fluid to passinto the channel when the valve is open, and a continuity detectorcoupled to the channel at the second end, wherein the continuitydetector may be activated when the fluid contacts the continuitydetector, wherein the continuity detector may be further configured toprovide a signal to close the valve and remove the fluid from thechannel.

In some embodiments, the substrate may include a piezoelectric material.In some embodiments, the piezoelectric material may be configured to beactivated by the signal provided by the continuity detector, whereinactivation of the piezoelectric material may close the valve and removethe fluid from the channel. In some embodiments, activation of thepiezoelectric material may remove the fluid from the channel at least inpart by contracting the channel and ejecting the fluid through anopening at the second end of the channel.

In some embodiments, the apparatus may further include a seal coupled toa perimeter of the surface of the substrate, wherein the seal may beimpermeable to fluids. In some embodiments, the seal may include anadhesive material that may be configured to adhere the substrate toanother surface.

In some embodiments, the apparatus may include an absorbent materialcoupled to the surface of the substrate, wherein the absorbent materialmay include a portion proximate the first end of the channel. In someembodiments, the absorbent material may be saturated with a primingfluid. In some embodiments, the absorbent material may include abranched conduit system configured to draw fluid from another surface incontact with the absorbent material to the valve. In some embodiments,the absorbent material may comprise a sponge or other porous material, agel (such as a hydrogel), an absorbent woven material, a fabric, anabsorbent fibrous material, or an arrangement of capillaries (such ascapillaries etched into a polymer or other material). In some examples,a woven or otherwise fibrous or structured material may be formed froman otherwise non-absorbent material, in which voids and channels betweenthe fibers and/or other structures may be used to absorb a volume ofwater. In some examples, capillaries (such as fluidic channels, fluidconduits, microchannels, microtubes, and the like) may be configured todraw fluid from a skin surface of a subject using capillary forces, anddirect the fluid to one or more pump locations, such as one or morepiezoelectric pumps. Capillaries may be arranged in a branchedarrangement, the branches being configured to draw fluid to one or morepump locations.

In some embodiments, the apparatus may further include a clock coupledto the continuity detector, wherein the clock may be configured tomeasure a time period and reset when the continuity detector isactivated, and a processor coupled to the clock, wherein the processormay be configured to receive the time period from the clock andcalculate a rate of flow of the fluid through the channel, based atleast in part on the time period from the clock and the volume of thechannel. In some embodiments, the processor may be at least a portion ofa computing device, for example, computing device 600. In someembodiments, the clock may also be included in the computing device.

In some embodiments, the substrate may include an electromagneticactuator. In some embodiments, the volume may be a volume between 100nanoliters and 10 microliters. In some embodiments, the apparatus mayfurther include an electrochemical sensor coupled to the channel at thesecond end, wherein the electrochemical sensor may be configured tosense a chemical in the fluid.

In some embodiments, an apparatus may be configured as a wearablesensor, for example being supported on a body portion of a livingsubject using one or more straps, adhesive patches, clips, and the like.In some examples, an apparatus may be combined with other functionality,such as one or more of a wristwatch, cardiac monitor, other medicalmonitoring device, internet device, communication device, ahead-supported apparatus, and the like.

In some examples, described approaches provide an improved method ofmonitoring the hydration state of a living subject, such as a human(such as an athlete, a medical patient, and the like), or non-humananimal. In some examples, improved hydration management of patients withcardiovascular and/or renal complications may be achieved, as well aspatients with a fever. In some examples, automatic hydration of apatient may be initiated, for example using an automated saline infusionbased on hydration status information, or by providing instructions tothe living subject or a caregiver therefor to administer fluid to theliving subject.

In some examples, a flow rate sensor as described in examples herein maybe used in an improved environmental sensor (for example, in combinationwith chemical analysis techniques for pollution monitoring, waterquality sensing, and the like), microfluidic devices, chemicalanalytical devices, biochemical analytic devices, and the like.

In some examples, an apparatus may be calibrated to an individualconfiguration or subject. In some examples, a system may monitor asubject's sweat rate over a time interval, and afterwards compared withanother measurement of sweat rate, such as a wash-down method, weightmonitoring, or other approach. In some examples, a reference absorbentpad may be placed on a subject's body, and the pad can be weighed beforeand after an exercise session or other time interval to determine theamount of fluid absorbed by the reference absorbent pad. The fluidamount may be compared to the apparatus measurements, e.g. during thesame time interval, from an apparatus located in a similar location, forexample, symmetrically positioned about the body. In some examples, anapparatus may be placed on a left part of the body (such as a left arm,leg, or torso), and a reference absorbent pad placed on a similarlocation on the right part of the body (or vice versa). A referenceabsorbent pad may be placed adjacent or otherwise proximate anapparatus.

A calibration process may be repeated at intervals to maintain orimprove the apparatus accuracy. In some examples, an apparatuscalibration may include digital imaging or 3D modeling of the channel tomeasure the volume of the channel. In some example, calibration mayinclude running the apparatus and collecting and measuring fluid at theexit point using another method, for example using volumetric or massbased measurements of the collected fluid. Determining an average valueof the cycle volume, and optionally the variance of the measurements,may be useful in determining the sweat rate and hydration data.

In some examples, a software program, for example executed on aprocessor of the apparatus or other device in communication with theapparatus, may be used to analyze hydration data. In some examples,hydration data provided by an apparatus may be analyzed along with otherdata, such as one or more of other data related to hydration status,exercise intensity (e.g. using data provided by an exercise machine,accelerometer mounted on the subject body, and the like), subjectmovement, speed (e.g. as provided by a speed sensor, global positioningsystem, and the like), heart rate, ambient temperature, body temperature(such as skin temperature and/or core body temperature), sweatcomposition, and the like, and may provide real-time indication ofsubject hydration status. In some examples, a software program may alsoallow input of other related data (such as a subject's sex, age, weight,species, and other health statistics), ambient data such asweather-related conditions (such as heat, humidity, and the like),geolocation data (including position, altitude, speed, and the like),and/or other information. In some examples, a software program may allowinput of consumed items (such as what the person ate and drank, andwhen), as well as other outputs (such as time and quantity of urination,defecation, vomiting, and the like). A software program may be used tocreate a model of a subject's total body water turnover, for example fora time interval and/or activity. In some examples, the determined totalbody water turnover model may be used to determine a hydration status ofthe subject during a time period without measurements by the apparatus.For example using a sub-set of sensors such as a heart rate sensor andan ambient temperature sensor.

In some examples, an apparatus may include one or more additionalsensors, or may in communication with other devices providing data. Insome examples, an apparatus may further comprise one or more of anoptical sensor (for example sensitive to one or more wavelengths orspectral bands), an IR sensor, and/or an electrochemical sensor (e.g.configured to provide data related to sweat composition such as ionconcentration and/or ion composition, lactate concentration, osmolarityof the sweat, and the like). Additional sensors may be used tointerrogate the sweat at any point in the apparatus, for exampleproximate a conductivity sensor, at any flow channel, and the like.

In some examples, a chamber may comprise a rigid polymer (such as HDPE,ABS, and the like), and may comprise a molded polymer and/or 3D printedcomponents. In some examples, a seal may comprise an O-ring that isadhered to the bottom surface. In some examples, an absorbent materialof a size and shape appropriate to the sensor can be inserted andoptionally adhered to the internal portion of the chamber. In someexamples, a hole for the valve may be provided e.g. by molding,drilling, and the like. A piezoelectric material, such as PVDF orinorganic piezoelectric material, may be adhered to or otherwise locatedat the top surface of the chamber, and electrodes disposed thereon andelectrically connected to a control circuit. A lid may be located on topof the channel to create a water-tight seal over the channel using anyappropriate configuration.

In some examples, a method, such as a method of determining a sweat rateand/or a hydration state of a living subject, comprises collecting afluid from a bodily surface of the living subject (such a portion of askin surface) into a body-worn device, filling a channel of thebody-worn device with the fluid, measuring, using the body-worn device,a time it takes to fill the channel with the fluid, removing the fluidfrom the channel, and calculating, using the body-worn device, a rate offlow of the fluid based, at least in part, on the time it takes to fillthe channel with the fluid. In some examples, the fluid comprises sweat.In some examples, the method may further comprise calculating a rate ofperspiration of a living subject based, at least in part, on the rate offlow of the fluid, and, in some examples, using a determined area of thebodily surface from which the fluid is collected.

The present disclosure is not to be limited in terms of the particularexamples described in this application, which are intended asillustrations of various aspects. Many modifications and examples can bemade without departing from its spirit and scope, as will be apparent tothose skilled in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to thoseenumerated herein, will be apparent to those skilled in the art from theforegoing descriptions. Such modifications and examples are intended tofall within the scope of the appended claims. The present disclosureincludes the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is to be understoodthat this disclosure is not limited to particular methods, reagents,compounds compositions or biological systems, which can, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular examples only, and is notintended to be limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.).

It will be further understood by those within the art that if a specificnumber of an introduced claim recitation is intended, such an intentwill be explicitly recited in the claim, and in the absence of suchrecitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to examples containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. In addition, even if a specificnumber of an introduced claim recitation is explicitly recited, thoseskilled in the art will recognize that such recitation should beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, means at leasttwo recitations, or two or more recitations).

Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together, etc.). In those instances where a conventionanalogous to “at least one of A, B, or C, etc.” is used, in general sucha construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the likeinclude the number recited and refer to ranges which can be subsequentlybroken down into subranges as discussed above. Finally, as will beunderstood by one skilled in the art, a range includes each individualmember. Thus, for example, a group having 1-3 items refers to groupshaving 1, 2, or 3 items. Similarly, a group having 1-5 items refers togroups having 1, 2, 3, 4, or 5 items, and so forth.

While the foregoing detailed description has set forth various examplesof the devices and/or processes via the use of block diagrams,flowcharts, and/or examples, such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples can be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In one example, severalportions of the subject matter described herein may be implemented viaApplication Specific Integrated Circuits (ASICs), Field ProgrammableGate Arrays (FPGAs), digital signal processors (DSPs), or otherintegrated formats. However, those skilled in the art will recognizethat some aspects of the examples disclosed herein, in whole or in part,can be equivalently implemented in integrated circuits, as one or morecomputer programs running on one or more computers (e.g., as one or moreprograms running on one or more computer systems), as one or moreprograms running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of skill in the art in light of this disclosure.For example, if a user determines that speed and accuracy are paramount,the user may opt for a mainly hardware and/or firmware vehicle; ifflexibility is paramount, the user may opt for a mainly softwareimplementation; or, yet again alternatively, the user may opt for somecombination of hardware, software, and/or firmware.

In addition, those skilled in the art will appreciate that themechanisms of the subject matter described herein are capable of beingdistributed as a program product in a variety of forms, and that anillustrative example of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude, but are not limited to, the following: a recordable type mediumsuch as a floppy disk, a hard disk drive, a Compact Disc (CD), a DigitalVideo Disk (DVD), a digital tape, a computer memory, etc.; and atransmission type medium such as a digital and/or an analogcommunication medium (e.g., a fiber optic cable, a waveguide, a wiredcommunications link, a wireless communication link, etc.).

Those skilled in the art will recognize that it is common within the artto describe devices and/or processes in the fashion set forth herein,and thereafter use engineering practices to integrate such describeddevices and/or processes into data processing systems. That is, at leasta portion of the devices and/or processes described herein can beintegrated into a data processing system via a reasonable amount ofexperimentation. Those having skill in the art will recognize that atypical data processing system generally includes one or more of asystem unit housing, a video display device, a memory such as volatileand non-volatile memory, processors such as microprocessors and digitalsignal processors, computational entities such as operating systems,drivers, graphical user interfaces, and applications programs, one ormore interaction devices, such as a touch pad or screen, and/or controlsystems including feedback loops and control motors (e.g., feedback forsensing position and/or velocity; control motors for moving and/oradjusting components and/or quantities). A typical data processingsystem may be implemented utilizing any suitable commercially availablecomponents, such as those typically found in datacomputing/communication and/or network computing/communication systems.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures can beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable”, to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

While various aspects and examples have been disclosed herein, otheraspects and examples will be apparent to those skilled in the art. Thevarious aspects and examples disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

1. An apparatus, comprising: a substrate having a surface; a channel ofa volume defined, at least in part, by the substrate, wherein thechannel has a first end and a second end; a valve coupled to the channelat the first end, wherein the valve is configured to allow a fluid topass into the channel when the valve is open; and a continuity detectorcoupled to the channel at the second end, wherein the continuitydetector is activated when the fluid contacts the continuity detector,wherein the continuity detector is further configured to provide asignal to close the valve and remove the fluid from the channel.
 2. Theapparatus of claim 1, wherein the substrate comprises a piezoelectricmaterial.
 3. The apparatus of claim 2, wherein the piezoelectricmaterial is configured to be activated by the signal provided by thecontinuity detector, wherein activation of the piezoelectric materialcloses the valve and removes the fluid from the channel.
 4. Theapparatus of claim 3, wherein activation of the piezoelectric materialremoves the fluid from the channel at least in part by contracting thechannel and ejecting the fluid through an opening at the second end ofthe channel.
 5. The apparatus of claim 1, further comprising a sealcoupled to a perimeter of the surface of the substrate, wherein the sealis impermeable to fluids.
 6. The apparatus of claim 5, wherein the sealcomprises an adhesive material configured to adhere the substrate toanother surface.
 7. The apparatus of claim 1, further comprising anabsorbent material coupled to the surface of the substrate, wherein theabsorbent material includes a portion proximate the first end of thechannel.
 8. The apparatus of claim 7, wherein the absorbent material issaturated with a priming fluid.
 9. The apparatus of claim 7, wherein theabsorbent material includes a branched conduit system configured to drawfluid from another surface in contact with the absorbent material to thevalve.
 10. The apparatus of claim 1, further comprising: a clock coupledto the continuity detector, wherein the clock is configured to measure atime period and reset when the continuity detector is activated; and aprocessor coupled to the clock, wherein the processor is configured toreceive the time period from the clock and calculate a rate of flow ofthe fluid through the channel, based at least in part on the time periodfrom the clock and the volume of the channel.
 11. The apparatus of claim10, wherein the rate of flow of the fluid through the channel iscalculated, based at least in part on a number of continuity detectoractivations.
 12. The apparatus of claim 10, wherein the rate of flow ofthe fluid through the channel is calculated, based at least in part on anumber of times the fluid is removed from the channel.
 13. The apparatusof claim 1, wherein the substrate comprises an electromagnetic actuator.14. The apparatus of claim 1, wherein the volume is a volume between 100nanoliters and 10 microliters.
 15. The apparatus of claim 1, furthercomprising an electrochemical sensor coupled to the channel at thesecond end, wherein the electrochemical sensor is configured to sense achemical in the fluid.
 16. A method, comprising: collecting a fluid froma bodily surface into a body-worn device; filling a channel of thebody-worn device with the fluid; measuring, using the body-worn device,a time it takes to fill the channel with the fluid; removing the fluidfrom the channel; and calculating, using the body-worn device, a rate offlow of the fluid based, at least in part, on the time it takes to fillthe channel with the fluid.
 17. The method of claim 16, wherein thefluid comprises sweat.
 18. The method of claim 17, further comprisingcalculating a rate of perspiration of a user based, at least in part, onthe rate of flow of the fluid.
 19. The method of claim 16, wherein anarea of the bodily surface is known.
 20. A system, comprising: a sensorconfigured to monitor a flow of a fluid from a bodily surface areathrough a channel of a volume; a first processor configured to receivesignals from the sensor and calculate a flow rate of the fluid; and acomputing device, including a second processor configured to receive theflow rate of the fluid from the first processor and combine the flowrate of the fluid with additional data to calculate a health status of auser.
 21. The system of claim 20, wherein the additional data includesat least one of a temperature, an exercise intensity of the user, or aheart rate of the user.
 22. The system of claim 20, wherein the fluidcomprises sweat produced by the user.
 23. The system of claim 22,wherein the second processor is further configured to calculate aperspiration rate of the user based, at least in part, on the flow rateof the fluid.
 24. The system of claim 20, wherein the health status is ahydration status of the user.